Female hippopotamus, Renu spends time with her newly born calf in an enclosure at the Assam State Zoo in Guwahati on July 20, 2015. The captive-bred calf was born on the night of June 15. (Photo by Biju Boro/AFP Photo)

A white Bengali tigress carries one of her four cubs in their enclosure in Xantus Janos Zoo in Gyor, 120 kms west of Budapest, Hungary, Friday, July 24, 2015. The cubs were born late May. (Photo by Csaba Krizsan/MTI via AP Photo)

One of four white Bengali tiger cubs born at the end of May in Xantus Janos Zoo snarls in their enclosure in Gyor, 120 kms west of Budapest, Hungary, Friday, July 24, 2015. (Photo by Csaba Krizsan/MTI via AP Photo)

A white Bengali tigress carries one of her four cubs in their enclosure in Xantus Janos Zoo in Gyor, 120 kms west of Budapest, Hungary, Friday, July 24, 2015. (Photo by Csaba Krizsan/MTI via AP Photo)

A white Bengali tigress stands with her four cubs in their enclosure in Xantus Janos Zoo in Gyor, 120 kms west of Budapest, Hungary, Friday, July 24, 2015. (Photo by Csaba Krizsan/MTI via AP Photo)

One of four white Bengali tiger cubs born at the end of May in Xantus Janos Zoo walks in their enclosure in Gyor, 120 kms west of Budapest, Hungary, Friday, July 24, 2015. (Photo by Csaba Krizsan/MTI via AP Photo)

Elephants and their keepers use the pool water to cool down at the zoo Hellabrunn in Munich, Germany, Wednesday, July 22, 2015. (Photo by Matthias Schrader/AP Photo)

Three week old white lions relax in their cage with their mother Azira at a private zoo in Borysew, Poland, Sunday, July 26, 2015. They are the third litter by Azira, fathered by Sahim, who has, however, been separated from them as a precaution. (Photo by Czarek Sokolowski/AP Photo)

People watch three-months-old white Bengal tiger in the enclosure at a private zoo in Borysew, Poland, on Sunday, July 26, 2015. They were rejected by their mother after birth and have been bottle-fed by the zoo staff. (Photo by Czarek Sokolowski/AP Photo)

One-month-old baby drill monkey Pinto plays in his enclosure in Munich's zoo Hellabrunn, Germany July 22, 2015. (Photo by Michaela Rehle/Reuters)

Female mandrill monkey (Mandrillus leucophaeus) Afi, feeds her newborn baby at the zoo Hellabrunn in Munich, Germany, Wednesday, July 22, 2015. (Photo by Matthias Schrader/AP Photo)

Seven-month-old lion cubs, Mona and Alex, are seen inside their enclosure after their arrival in Amman, Jordan, July 23, 2015. Two lion cubs rescued from Gaza earlier in July have found a new home at a wildlife sanctuary in neighbouring Jordan. The seven-month-old cubs were removed from the Gaza home of a Palestinian refugee, according to Mahdi Quatrameez, the Chief Executive Officer (CEO) of the Amman-based Al Ma'wa for Nature and Wildlife (MNW). (Photo by Muhammad Hamed/Reuters)

Seven-month-old African lion cubs, Mona and Alex, play inside their enclosure after their arrival in Amman, Jordan, July 23, 2015. (Photo by Muhammad Hamed/Reuters)

A ten days old South American sea lion pup sits next to its mother Lunita at the “Tiergarten Schoenbrunn” Zoo in Vienna, Austria, July 28, 2015. The pup was born in the zoo and weighs about 14 kilograms (30 pounds). (Photo by Leonhard Foeger/Reuters)

A ten days old South American sea lion pup plays around at the “Tiergarten Schoenbrunn” Zoo in Vienna, Austria, July 28, 2015. (Photo by Leonhard Foeger/Reuters)

A ten days old South American sea lion pup sits next to its mother Lunita at the “Tiergarten Schoenbrunn” Zoo in Vienna, Austria, July 28, 2015. (Photo by Leonhard Foeger/Reuters)

A ten days old South American sea lion pup sits next to its mother Lunita at the “Tiergarten Schoenbrunn” Zoo in Vienna, Austria, July 28, 2015. (Photo by Leonhard Foeger/Reuters)

A polar bear holds onto a block of ice at a zoo in Daejeon, 160 km south of Seoul, to stay cool amid high temperatures that hover around 30 degrees celsius on 28 July 2015. (Photo by EPA/Yonhap)

A seal cools off at Belgrade Zoo during a heatwave on July 21, 2015. (Photo by Andrej Isakovic/AFP Photo)

SLankan elephants bathe in a lake at the Yala National Park in the southern district of Yala some 250kms southwest of Colombo on July 24, 2015. The Yala National Park is the most visited and second largest national park in Sri Lanka. (Photo by Ishara S.Kodikara/AFP Photo)

Jiff Pom seen at the Los Angeles Premiere of AwesomenessTV and Defy Media's “SMOSH: THE MOVIE” held at Westwood Village Theatre on Wednesday, July 22, 2015, in Los Angeles. (Photo by Eric Charbonneau/Invision for AwesomenessTV/AP Images)

Tilly the three-year-old Yorkshire Terrier is blown by the wind, July 27, 2015, at Porthcawl, South Wales, where high winds are battering the UK. (Photo by Ben Birchall/AP Photo/PA Wire)

A camel yawns before competing on July 24, 2015 in the western town of Pornichet before competing in one leg of the first French camels race championship. (Photo by Georges Gobet/AFP Photo)

A three-days old bonobo baby sleeps on the belly of its mother Kutu in the zoo in Frankfurt, Germany, Tuesday, July 21, 2015. (Photo by Michael Probst/AP Photo)

White mother Bengali tiger “Manji” with one of her two white cubs in their enclosure at Zoo Safari in Borysew, central Poland, 24 July 2015. Two rare white tigers were born in Zoo Safari on 14 July. (Photo by Grzegorz Michalowski/EPA)

An elephant takes a bath in Munich's zoo Hellabrunn, Germany July 22, 2015. (Photo by Michaela Rehle/Reuters)

A 35-year-old polar bear eats a piece of watermelon at Belgrade Zoo during a heatwave on July 21, 2015. In Serbia where the meteoalarm has been raised to “red”, extremely hot weather with temperatures up to 39 degrees Celsius is expected to continue over the next several days. (Photo by Andrej Isakovic/AFP Photo)

Black-capped Capuchin monkeys stand inside their cage at the Attica Zoological Park in Spata, near Athens, on July 23, 2015. Between a zoo struggling to import food for its animals and associations overwhelmed by the abandonment of cats, the crisis in Greece, in addition to its cruel human impact, also affects animals. (Photo by Aris Messinis/AFP Photo)

A chimpanzee drinks frozen fruit juice from a bottle at the Attica Zoological Park in Spata, near Athens, on July 23, 2015. (Photo by Aris Messinis/AFP Photo)

A green turtle is held as marine turtle specialists prepare to release the more than 570 baby sea turtles, including the Loggerhead and Green turtles, into the Atlantic Ocean in a joint effort between the Coast Guard and the Gumbo-Limbo Nature Center on July 27, 2015 in Boca Raton, Florida. The sea turtles hatchlings come from turtle nests located along beaches throughout Florida, which are the primary nesting grounds for Loggerhead sea turtles. (Photo by Joe Raedle/Getty Images)